Coronary artery stenosis is a good indicator of coronary artery disease, and various imaging and diagnostic techniques have been developed to enable the identification and visualisation of regions that include stenoses.
Catheter coronary angiography has traditionally been considered to be the most accurate imaging technique for assessing coronary artery stenosis. However, catheter coronary angiography is an invasive process, requiring localisation of the catheter to each coronary ostium, which is uncomfortable for the patient and can pose some danger. Furthermore, the technique uses X-Ray fluoroscopy, which involves subjecting the patient to a high dose of radiation. FIG. 1 shows a 2D image obtained using catheter coronary angiography.
Calcium scoring and contrast-enhanced CT angiography (CCTA) scans may still be carried out, in addition to catheter coronary angiography procedures. However, cardiologists are used to viewing 2D images obtained using angiography, and can struggle to assess CTA scans from 2D CTA slice data alone. It is known to present 2D images obtained from CCTA scans but such images, in contrast to catheter coronary angiography images, usually include significant calcification features, when such features are present in the patient. The presence of such calcification features can make the assessment of stenosis or other conditions difficult or impossible. FIG. 2 is a 2D image obtained from a CCTA scan in which significant calcification features are visible. Similar issues can arise with stents or other features associated with a vessel, for example surgical clips, pacemakers or other metallic artefacts.